The invention relates to a process for reducing the volume of materials by compression in a screw extruder and to a screw extruder for performing this process.
Numerous different screw extruder constructions are known. They are mainly used in the plastic processing industry and with the aid thereof it is possible to produce semifinished plastic articles, as well as finished plastic articles of the most varied types. It is known that during the processing of many plastics, the screw extruders and in particular the screw must be constructed in accordance with the material to be processed, which leads to a large number of different extruder constructions. Consequently, there is an equally large number of screw extruder manufacturers.
The number of screw extruder types would be further increased if it were necessary to use a screw extruder for processing further organic or inorganic materials, other than plastics. In addition, screw extruders are relatively complicated machines, which can really only be operated by trained personnel. Thus, difficulties may occur when such screw extruders are, for example, used in developing countries.
In the field of waste processing, it is ever more pressing in view of the harm to the environment, to use processes and plants enabling waste materials to be processed with a low expenditure of energy and enabling them to be brought into a form in which they can be reused or more easily destroyed, e.g. incinerated.
Thus, the problem of the invention is to so develop a process and a screw extruder for processing materials, that the same process steps can be used for processing a large number of different materials and consequently the extruder can be constructed in such a way that there is no need for modifications to the basic construction, even when processing widely differing materials. These materials cover flowable and free-flowing mixtures of preferably organic substances, waste materials and mixtures of the most varied types, e.g. sewage sludge, manure, refuse or garbage, etc. It also covers inorganic mixtures, e.g. chemical waste, which must be processed in such a way that they are made harmless or can easily be destroyed.